ABSTRACT
Sport represents a stress for the body. Many metabolic and cardiorespiratory changes are known during physical activity. However, little is known in swimmers particularly during head-out immersion. To determine the metabolic and cardiorespiratory response in swimmers during head-out immersion. The energetic, cardiovascular function and ventilatory requirements of a 10 min steady state arm exercise performed by 13 healthy subjects in air and during immersion up to the hip in 26[degree sign]C water were compared. The same ergometric work load was achieved with an average maximum oxygen uptake of 3.9 +/- 2.63 l/min in air versus 3.55 +/- 2.48 l/min in water [p=0.953]. During exercise, the average values of minute ventilation, ventilation equivalent for oxygen, ventilation equivalent for CO2, peak expiratory flow, respiratory exchange ratio and heart rate were not different in water and in air. However, first ventilatory threshold was significantly higher in water than in air. The mean value of the first ventilatory threshold was 0.89 +/- 0.23 l/min in air, and 1.08 +/- 0.23 l/min in water immersion; [p=0.016]. These results suggest that training swimmers favoring immersion [weight belts] may improve their aerobic capacity